Determination of 54 Volatile Hydrocarbons by Thermal Desorption-Gas Chromatography in Workplace Air / 分析化学

ABSTRACT

A method was developed for the determination of 54 volatile hydrocarbons in workplace air by thermal desorption/gas chromatography-hydrogen flame ionization detector. The workplace air was adsorbed by Tenax-TA thermal desorption tubes, then desorbed by thermal desorption and detected by gas chromatography. The experimental results indicated that the coefficients efficiency of 1,1-dichloroethylene, dichloromethane, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, 2,2-dichloropropane, bromochloromethane, 1,1,1-trichloroethane, 1,2-dichloroethane, 1,1-dichloropropene were 0.9941-0.9986. The detection limits of bromochloromethane, dibromomethane, trichloromethane, bromodichloromethane, 2,2-dichloropropane, dibromochloromethane, bromoform were 5.4-10.3 ng, the minimum detectable concentration was 0.01-0.1 mg/m~3 (the air volume=0.5 L). The coefficients efficiency of other 38 volatile hydrocarbons was above 0.999, the minimum detectable concentration were 0.001-0.01 mg/m~3. The detection limits of alkenes were 0.4-2.7 ng, alkanes 1.4-3.7 ng, aromatic hydrocarbons 0.2-1.0 ng and naphthalene 2.2 ng. The desorption efficiencies of 54 volatile hydrocarbons were 92.1%-113.1% and the relative standard deviations(RSDs) were 0.6%-17.4%. Except for the RSD values of cis-1,2-dichloroethylene, 1,1-dichloroethane, 1,1,1-trichloroethane, 1,1-dichloroethylene, 2,2-dichloropropane, trichloromethane, trans-1,2-dichloroethylene, dichloromethane, bromochloromethane were 5.1%-17.4%, those of other volatile hydrocarbons were below 5%;The experimental results indicated that the breakthrough capacities of 9 volatile hydrocarbons were 400-4000 ng, those of the other volatile hydrocarbons were above 10 μg. Except for the loss rates of 2,2-dichloropropane, bromodichloromethane were 10%-15% in stable experiment, those of other volatile hydrocarbons in Tenax desorption tubes were below 5%, which indicated that 54 volatile hydrocarbons stored in Tenax tubes were stable. The method is a quick and accurate for the detection of volatile hydrocarbons in workplace air.